Narrow Results

Up to the eighties of the last century high magnetic fields had been thought to be rather useless for metrology. This opinion changed very abruptly in 1980 after the discovery of the quantum Hall effect. This effect allows the reproduction of quantized resistance values with an extremely low uncertainty which today is of the order of 10^-9. Nowadays there is an intensive discussion to re-define the unit of mass, the kilogram, by a definition of the Planck constant h, which can be determined by a so-called watt balance which makes use of the quantum Hall effect and thereby of high magnetic fields.

In the early eighties, the development of ballistic absolute gravimeters based on laser interferometer opened the doors to new research areas in various scientific domains such as geodesy, geophysics or metrology. After a brief overview of the most used technique for gravity measurements, the implication of gravity in the context of an improved SI, especially for a new definition of the mass unit kg, will be presented.